Method of making a closure and terminal construction for electrolytic devices



Jan. 8, 1957 J. B. BRENNAN 2,776,457

METHOD OF' MAKING A CLOSURE AND TERMINAL CONSTRUCTION FOR ELECTROLYTICDEVICES Filed Nov. 27, 1951 1N VEN TOR.

Joss/PH 5. BKE/Y/VHN ATTORNEYS nited States METHOD F MAKING A CLOSUREAND TEAL CNSTRUCTION FR ELEC- TROLYTC DEVICES This application is acontinuation-impart of my c0- pending application Serial No. 558,864filed October 16,

i944 now abandoned.

This invention relates to electrolytic devices and more particularly toa method of making a closure and terminal assembly for electrolyticdevices such as electrolytic condensers, rectiilers, lightning arrestorsand the like.

Such devices frequently comprise two or more elecrodes immersed in anelectrolyte disposed within a thin walled metallic container' such as athin Walled, drawn or extruded aluminum cup or can having one open end.lt is necessary to prevent leakage of the electrolyte from thecontainers and at the same time to provide for terminal connections ofthe electrodes. F[be terminals must extend to the exterior of thecontainers and ordinarily must be insulated from each other and from thecontainer. Heretofore, it has been difficult to provide permanentlyleak-proof assemblies, for pressure alone has been relied on for sealing:and pressure sealing often is not lealsproof against the capillaryaction and crystal growth encountered in devices such as electrolyticcondensers.

A general object of the present invention, therefore, is to provide amethod of making a simple and inexpensive closure and terminal assemblyfor such devices. Another object is the provision of a closure andterminal assembly which will remain leakproof in service.

Another object is to provide a method of making such an assembly whereinthe terminals are spaced from each other and from the container, andsupported in their spaced relationship by the closure member.

Still another object is to provide a method of making such an assemblywith inexpensive materials and rapidly.

A further object is to provide a method of making a terminal and closureassembly which will be permanently leakproof and in which the terminalsand container are positively spaced and electrically insulated from eachother.

Further objects and advantages of my invention will become apparent fromthe following description of preferred forms thereof, reference beingmade to the accompanying drawings in which: y

Figure l illustrates an electrolytic device such as a condenser or thelike embodying one form of my invention, the upper part of the devicebeing shown in section to illustrate my closure and terminal assembly;

Figure 2 is a section as indicated by line 2--2 of Figure l and showingthe underside of the closure and terminal assembly;

Figure 3 is an enlarged, fragmentary detail of the seal between theclosure member and the container;

Figure 4 is an enlarged sectional detail showing one of the terminalmembers supported in the closure member;

Figure 5 is a View similar to Figure l but illustrating a slightlymodified form of my invention;

Figure 6 is lan enlarged sectional detail through one of the terminalmembers of Figure 5;

' atent 1 Figure 7 is a similar sectional detail of a modified form ofterminal member for the assembly shown in Figure 5;

Figure 8 is a View similar to Figure l, but showing a still furthermodification or" my invention;

Figure 9 is a plan view of the assembly shown in Figure S as indicatedby the line 9-& of Figure 8;

Figure lll is exploded view showing the parts making up the closure andterminal assembly of Figure 8; and

Figure ll is an enlarged sectional detail of the assembly illustrated inFigure 8, showing one of the terminal members.

Briefly, my invention, in its preferred forms, contemplates theprovision of a closure and terminal assembly for thin walled metalliccontainers comprising a closure member preferably in the form of a disccomposed of a suitable insulating material, the periphery of the discbeing joined or cemented to the container, preferably by a ieakproofplastic bond such as the bond produced by the cycleweld process. rlhedisc is provided with as many openings as there are terminals. Theseopenings in the insulating discs are closed by metallic discs or cups orshoulders which are cemented to the insulating disc in leakproofrelationship, and the terminal members are welded, soldered or otherwisesuitably secured to the metallic discs. l may provide, for example, aninternal terminal member extending from one electrode of theelectroyltic device to the inner side of one of the metallic dscs, theexterior of the metallic disc being connected to an external circuitthrough an external terminal member welded, soldered or otherwisesecured to the exterior of the same dis-c. Thus an entirely lealtproofconnection is provided, the terminal members are supported in thedesired positions by the disc of insulating material to which themetallic discs are secured, and the internal and external terminalmembers may be made of materials best suited for their respectiveduties,

In Figures l to 4 of the drawings I have shown one form of my inventionas adapted to an electrolytic device such `as an electrolytic condensercomprising an electrode assembly indicated diagrammatically at itil,immersed in an electrolyte 11 within a thin Walled aluminum containerl2. The aluminum container l2 is open at its upper end and is deformedinwardly as shown to provide a shoulder r1.3 adapted to engage theunderside of the insulating disc i4. The periphery of the disc i4 tsclosely within the wall l5 of the container l2, and the upper edge ofthe container is pressed, rolled or spun inwardly as at i6 therebyretaining the disc l in position.

The disc i4 may be composed of any suitable insulating material. Hardrubber, ber, glass, porcelain or other ceramic material, variousplastics, and other natural or synthetic insulating materials aresuitable. For example, l may use discs composed of plastics such asresins of the phenol formaldehyde, urea formaldehyde, styrene, ethylcellulose and vinyl types. The resins may be used either With or withoutiiber or fabric reinforcing materials. Hard ber discs coated with aplastic bonding material may be employed. The selection of theparticular insulating material will depend upon the service to which thedevice is put. the nature of the electrolyte and the cost of variousmaterials. For most purposes discs composed of resins of the phenolformaldehyde type are extremely satisfactory. Glass, porcelain orceramics may be employed where cost lis an important consideration andWhere there is little likelihood of shock or rough treatment.

In order to secure the disc in place with a permanently leakproof jointwhich also has high mechanical strength, l preferably cement the disc tothe inner surface of the container 12. This cementing or bondingoperation is preferably carried out by the process known as cycleweldingand developed by Chrysler Corporation. According to this process thecementing medium, which is a thermosetting plastic material, is appliedto the surfaces to be joined by brushing, spraying or dipping, ispermitted partially to dry and then the assembled parts are subjected toheat and pressure to vulcanize or otherwise cure the cementing material,producing a permanent bond which has ample strength and which adheres toboth the metal and the plastic or other insulating material so stronglythat a permanent bond is produced which is not destroyed by differencesin expansion of the parts due to variations in temperature.

Other bonding materials may be used in place of the cycleweld cement.The bonding material selected should adhere strongly to the containerand to the insulating disc. This result is ordinarily obtained, ibelieve, by providing cement that has high penetration, that is, cementwhich will penetrate and thus adhere to the minute pores of the surfacesto which it is to be joined. Also, after curing, the cement should notreact with or be soluble in the electrolyte. Thus, after curing, cementsintended for use in electrolytic condensers should not be soluble in orreact with water, various alcohols and solutions containing borax andboric acid. Also the material, after curing, should be free fromchlorides, or at least should be of such nature that it will not giveolf enough chlorides to contaminate the electrolyte. In the case ofelectrolytic condensers, the cured cement or bonding material shouldhave the ability to stand temperatures of from 80 to 90 C. for longperiods of time without substantial deterioration. Preferably, the curedbonding material should be an insulator so that the bonding materialitself would not furnish a conductive path in the event some of itshould be spilled on the surfaces of the insulating discs.

By such a bonding method, the insulating disc is permanently joined tothe aluminum container, and because of the relatively low cost ofmaterials and the rapidity of the operation, the bonding operation canbe carried out very economically. The resulting bond is indicateddiagrammatically in Figure 3 wherein the plastic bonding material isshown diagrammatically at 17 as extending be- 'tween and bondingtogether the cylindrical surface and adjacent lower and upper surfacesof the disc 14, and the inner cylindrical surface of the wall 1S, theupper surface of the shoulder 13 and the undersurface of the ange 16 ofthe container 12. The thickness of the bonding material .is necessarilyexaggerated throughout the drawings. In making this assembly, the partsare coated with the bonding material which is then oven dried orpermitted to dry in the air to the proper degree. Then the disc 14 isassembled with the container and the flange 16 which originally was ofcylindrical form, is rolled or spun into engagement with the uppersurface of the disc as shown in the drawing. The spinning operationsupplies the required pressure to the bonding material and accordinglywith this type of assembly, the final curing or vulcanizing operationcan be carried out merely by the application of heat to the bondingmaterial. Thus the equipment necessary to complete the bond is simplied,for the vulcanizing operation may be carried out merely by applying thenecessary heat to the exterior surfaces of the container adjacent thebonded areas by means of a simple heated metallic collar, for example.

In order to connect the electrode assembly to au external circuit,terminal members are required for each separate electrode in theassembly. In the pesent instance, I have shown the electrode assembly ashaving two terminal members 26 projecting therefrom. Such an arrangementwould be used with an ordinary electrolytic condenser having an anodeand a cathode. However, it is to be understood that in some instances,it may be necessary to provide more than two terminal members, and inothers, only a single terminal member may be required.

In order to connect the internal terminal members 20 with an externalcircuit, each terminal member 20 is welded, soldered or otherwisesuitably secured to a metallic disc 21. Each disc in turn is secured asby the cyclewelding or other suitable process to the insulating disc 14,preferably by bonding or cementing the metallic discs to the interiorsurface of the insulating disc as shown. The insulating disc isapertured adjacent the discs 21 as indicated at 22, to permit theexternal terminal members 23, which are welded, soldered or otherv/isesecured to the outer sides of the discs 21, to pass through the disc 14.The assembly is shown on an enlarged scale in Figure Here the internalterminal member 20 and external terminal member 23 have their endportions 24 and 25 bent parallel to the disc 21 and disposed on oppositesides of the disc so that both end portions can be secured to the discby a single spot welding operation, producing the aligned spot weldsindicated diagrammatically at 26 and 27. The cementing material forsecuring the disc 21 to the disc 14 is shown diagramamtically at 28.

In an electrolytic condenser, the internal terminal members and themetallic discs are preferably composed of aluminum or other film formingmetal. inasmuch as it is diflicult to make a soldered connection toaluminum, the external terminal members are preferably composed of ametal which can be soldered easily such as copper or tinned steel. Thus,the internal terminals and discs may be composed of materials which willnot contaminate the electrolyte or cause leakage in the condenser, andthe welded joint between these parts insures that the connection will beof low resistance and Will not deteriorate. The exterior terminals maybe made of material best suited to their particular function, for theydo not enter the interior of the condenser in any way, and hence noconsideration need be given to any possible reaction with theelectrolyte.

By this arrangement, I have provided a simple and -leakproof assemblywhich can be manufactured economically and rapidly. I prefer to providethe disc 14 with openings 22 before assembly with the other parts. Theterminals 20 and 23 are welded to the discs 21, making a sub-assembly,then discs 21 are secured to the disc 14. Thereafter the variouselements of the condenser are assembled and finally the operation ofsecuring the disc 14 within the container 12 is carried out. 'Ihisoperation can be carried out without subjecting the device to excessiveheat and without disturbing the assembled relationship of the parts. Inthe completed structure, the internal and external terminal members arerigidly spaced from each other by the disc 14 and are insulated fromeach other and from the container 12 by the disc 14. The bondingmaterial itself is also an insulator. There is no possibility ofleakage, for the openings in the disc 14 are completely closed by thediscs 21. Obviously, various types of terminal members can be employed.In some types of devices, the terminals may be soldered or brazed to thediscs 21 instead of being Welded as shown herein. If desired, the discs21 may be secured to the exterior of the disc 14 with the inner terminalmember 20 extending through the openings 22. In such an arrangement theexternal terminal members 23 might be omitted, external connectionsbeing made directly with the discs 21 by spring contact ngers or othersuitable means.

In the modification of my invention shown in Figures 5 and 6, all of theparts, with the exception of the discs 21, are substantially identicalwith those previously described and have been marked with the samereference characters. In this modification, however, instead of usingflat discs for sealing the openings in the disc 14 and interconnectingthe internal and external terminal members 26 and 23, I employ drawncup-shaped members 21a. The end portions 24 and 25 of the terminals 20and 23 are spot Welded or otherwise suitably secured to the bottomportions 29 of the cups, and the cups have cylindrical portions 30 whichfit closely within the openings 22 in the disc 14. The cups, which canbe manufactured economically on cyclist-making machines, are preferablyprovided with flanges 31 at their closed ends, and are hanged over as at32 after they have been assembled with the disc 14. The cement orbonding material extends between the cylindrical portions 39 and thecylindrical walls of the openings, and between the anges and the outersurface of the disc 14 immediately surrounding the openings, asindicated diagrammatically at 33. This construction is somewhat strongerthan the construction previously described and may locate the terminalmembers with somewhat greater accuracy, because of the it between thecylindrical portions of the cut member 21a and the walls of the openingsin the disc 14. Also in this form, the pressure required in the curingor vulcanizing ot' the bonding material is furnished by the close fitbetween the cylindrical portions 30 and the walls of the openings 22,and by the pressure exerted by the iiange 32. Thus the curing operationcan be carried out merely by the application of heat. As before, the uidtight con nections are made by the bonding or cementing methodspreviously described.

ln Figure 7 l. have shown a cup-shaped closure member generally similarto the members 21a of Figures 5 and 6 but modified in two particulars,either one of which may be used without the other if desired. Here themember 2lb is shaped generally like the member 21a previously describedand is secured in position in the same manner. However, the member iscomposed of a copper, steel, or brass inner portion 34 having analuminum coating 34a. By the use of such aluminum clad materials inproducing the cups, the portions of the cups exposed to the interior ofthe container and thus exposed to contact with the electrolyte arecomposed of aluminum which is satisfactory for electrolytic condensers,while the exterior portions of the cups are composed of a readilysolderable metal such as copper, brass or steel.

,ln this form, the inner terminal member is preferably substantiallyidentical with the terminal members previously described, and ifdesired, terminal members similar to the exterior terminals 23 may alsobe employed. However, the exterior terminal may be provided by thesimple expedient of extending a portion of the exterior flange 32a toprovide a terminal tab 23a. The tab 25u may be apertured as shown in thedrawing so that if desired an electrical connection can be made to thetab without requiring any soldering. As noted above, either of themodications disclosed in this figure may be used Without the other. Thusfor some purposes it may be satisfactory to provide an aluminum cladclosure member and use it with a conventional terminal, or solder anexternal connection, for example, to the flange 32u. ln other instances,it may be satisfactory merely to use the terminal tab 23a, but to makethe closure member out of a single metal such as aluminum. For otherpurposes it may be desirable to use the form shown in the Figure 7.

ln Figures 8 to ll, inclusive, l have shown a further modification ofthe invention wherein the insulating disc is or". thinner material andis reinforced by another metal disc. Here the electrode assembly iii isimmersed in the electrolyte 11 as above. However, the container 12a hasa cylindrical portion 35 at the open end thereof, extending beyond theinwardly projecting bead 36. The open end is closed by a disc 37composed of suitable insulating material such as vulcanized fiber or oneof the various materials heretofore mentioned, and having a peripheralange as at 38. The disc 37 is reinforced by a metallic disc 39 having aflange dit, the discs 37 and 39 being apertured as at di. and 42,respectively, with the apertures aligned to admit the external terminalmembers 43. The external terminal members are welded to metallic discs4d corresponding in function to the 4discs 21 heretofore described, andthese discs are in tuin Welded to the internal terminal members 45. Theassembly is completed by bonding the discs 44 to the underside of theinsulating disc 37 as indicated at 46 in Figure l1. Then the reinforcingmetallic disc, which is dimensioned to t closely within the insulatingdisc, is bonded thereto as indicated at 4] throughout substantially theentire contacting area of the two discs, and the flange 38 is bonded asindicated at 48 (Figure 8) to the portion 35 of the container. lpreferably employ one of the bonding proc* esses mentioned above, andthe operations of bonding the two discs together and of bonding the disc37 to the conr are preferably carried out simultaneously.

ly this arrangement, it is possible to employ a less expensiveinsulating disc and yet secure ample strength by provision of themetallic reinforcing disc. Here the terminal members are supported andinsulated from each other by the disc 37, and the arrangement is suchthat there is substantially no possibility of the external terminalmembers coming in contact with the external metallic reinforcing plate.As shown particularly in Figure li, the disc 44 is preferably of greaterdiameter than the opening 4Z in the metallic plate 39, and this openingis preferably of greater diameter than the opening 41 in the ber disc orinsulating disc 37. By this arrangement, the tiber or other insulatingmaterial is interposed between two layers of metal in the regionsurrounding the openings 4l. Thus the liber is reinforced by the metaland has ample strength to withstand any strains imposed upon it, eitherby the terminal members or by internal pressures developed within thecontainer.

ln the foregoing specification, i have described preferred forms of myinvention in considerable detail. it will be understood that variouschanges and modifications may be made therein Without departing from thespirit and scope of the invention. Accordingly, it is to be understoodthat my patent is not limited to the preferred forms described herein orin any manner other than by the scope of the appended claims.

l claim:

l. A method of making a leak-proof joint for an electrolytic condensercontainer closure capable of maintaining the container sealed attemperatures of to 90 C. comprising coating the portions to be joinedwith a thermosetting material, partially drying said coatings,assembling said coated portions thereafter face to face, pressing anddistorting at least one portion to partially embrace the other portion,and applying heat and pressure to said coatings to cure into a unitaryleak-proof joint capable `of standing temperatures of 80 to 90 C. overlong periods of time.

2. A method of sealing a terminal of an electrolytic device in anopening in an insulating disc through which the terminal extendscomprising attaching the terminals to the inner and outer sides of thebottom of a cup-shaped metal element having an outwardly extendingradial flange about the bottom portion, inserting the cup-shaped memberin the opening of the insulating disc with a layer of a thermosettingplastic bonding material which can be cured under pressure and heatbetween contacting surfaces of the disc and cup-shaped member, pressingthe free edge of the cup-shaped member outwardly and axially towards thebottom thereof to grip the portion of the disc surrounding the openingbetween the flange and deformed free edge, and pressing the plasticbonding material between the portions of the cup-shaped member and thedisc, and thereafter curing the bonding material by applying heat to theassembly.

3. Method of joining a conductive metallic member and a dielectricmember, comprising applying a layer of thermosetting bonding materialbetween the portions of the two members to be joined, pressing andpermanently deforming the metallic member to embrace with pressure theportion of the insulating member to be joined, and applying heat throughthe metallic member to react and cure the thermosetting bonding layer.

(References on following page) 2,776,467 7 4 References Cited in the lcof this patent 2,225,758

UNITED STATES PATENTS 1,924,893 Wackman Aug. 29, 1933 @347 2,084,973`10h11 June 22, 1937 5 376354 2,122,477 Leonard July 5, 1938 8 SteinDec. 24, 1940 Schnell Dec. 24, 194() Bohn June 3, 1941 Saunders Mar. 20,1945 Saunders May 22, 1945 iwi ""M-

1. A METHOD OF MAKING A LEAK-PROOF JOINT FOR AN ELECTROLYTIC CONDENSER CONTAINER CLOSURE CAPABLE OF MAINTAINING THE CONTAINER SEALED AT TEMPERATURES OF 80* TO 90*C. COMPRISING COATING THE PORTIONS TO BE JOINED WITH A THERMOSETTING MATERIAL, PARTIALLY DRYING SAID COATINGS, ASSEMBLING SAID COATED PORTIONS THEREAFTER FACE TO FACE, PRESSING AND DISTORTING AT LEAST ONE PORTION TO PARTIALLY EMBRACE THE OTHER PORTION, AND APPLYING HEAT AND PRESSURE TO SAID COATINGS TO CURE INTO A UNITARY LEAK-PROOF JOINT CAPABLE OF STANDING TEMPERATURES OF 80* TO 90*C. OVER LONG PERIODS OF TIME. 